What are SIC codes and why do they matter?
Standard Industrial Classification (SIC) codes are 5-digit numbers that describe your company's business activities[1]. Every company must choose at least one, and they're more important than most directors realize.
Your SIC codes affect:
- Corporation tax rates - Some activities qualify for reduced rates
- Insurance premiums - Insurers use SIC codes to assess risk
- Grant eligibility - Many grants are restricted to specific SIC codes
- Statistical reporting - Government surveys and data collection
- Banking relationships - Banks use SIC codes for compliance checks
Common Mistake
Many companies stick with generic codes like "Other professional, scientific and technical activities" (74909) when more specific codes could save them money on tax or unlock grant funding.
How to choose the right SIC codes
The key is being specific without being too narrow. You can register up to 4 SIC codes, so use them strategically:
Strategic SIC Code Selection
Primary Code (Most Important)
Your main business activity - this drives most decisions
Secondary Codes
Supporting activities or future business plans
Strategic Codes
Activities that unlock tax benefits or grants
Popular SIC codes by industry
Here are the most commonly used SIC codes across different sectors:
Technology & Software
- 62012 - Business software development
- 62020 - IT consultancy
- 63110 - Data processing and hosting
- 58290 - Other software publishing
Professional Services
- 70221 - Financial management
- 73110 - Advertising agencies
- 74201 - Architectural activities
- 69201 - Accounting services
Retail & E-commerce
- 47910 - Online retail
- 47190 - Other non-specialised stores
- 46900 - Non-specialised wholesale
- 82990 - Other business support
Construction & Property
- 41201 - Construction of residential buildings
- 68100 - Buying and selling property
- 68320 - Property management
- 43999 - Other specialised construction
Tax implications of your SIC codes
Some SIC codes come with tax advantages that many companies miss:
Tax-advantaged activities include:
- Research and development (various codes) - R&D tax credits up to 33%
- Manufacturing (codes 10000-33999) - Enhanced capital allowances
- Creative industries (various codes) - Creative industry tax reliefs
- Training providers (85000+) - Reduced corporation tax rates
- Environmental services - Enhanced deductions and grants
Common SIC code mistakes to avoid
Using Generic Codes
Codes like 74909 ("Other professional activities") tell you nothing and miss opportunities.
Forgetting to Update
Your business evolves - your SIC codes should too. Update them when you pivot or expand.
Choosing Too Many
Stick to 2-4 relevant codes. Too many makes you look unfocused to banks and investors.
Ignoring the Hierarchy
Your first SIC code is most important - make sure it's your primary business activity.
How to change your SIC codes
You can change your SIC codes at any time for free using Companies House WebFiling[2]:
Step-by-Step Process
- 1Log into Companies House WebFiling service
- 2Select "Change company information"
- 3Choose "Statement of capital" or "Annual return" depending on company type
- 4Update your SIC codes in the business activities section
- 5Submit the form (usually free, small fee for some company types)
Finding the right codes
The official SIC code lookup tool can be confusing. Here's how to navigate it effectively:
SIC code research strategy:
Regular Review is Essential
Review your SIC codes annually. Business activities change, new codes are added, and tax rules evolve. What was right two years ago might be costing you money today.
References
- [1]ONS Standard Industrial Classification Available at:www.ons.gov.uk/methodology/classificationsandstandards/ukstandardindustrialclassificationofeconomicactivities
- [2]Companies House - Change company information Available at:www.gov.uk/file-changes-to-a-company-with-companies-house